Unable to see her husband, who runs a convenience store, worrying about shoplifting, Mari consults with the security company where her sister Anna's husband works. Concerned for her sister's safety, Anna decides to work at a store as a shoplifting G-man with Mari, who has no experience. After the two of them stand at the store, they catch some shoplifters and feel relieved, but then Mari makes a false arrest. The two are deceived by the shoplifter, who they must have seen with their own eyes, and learn that there is a large thief group behind them.